Laser leveling device

ABSTRACT

The present invention provides a laser leveling device, which comprises a light emitting unit for irradiating a laser beam, a rotating unit for rotating the laser beam for scanning, and a means for turning off the scanning laser beam so that a spotlike is formed in a specific direction. By forming a reference spot light, and aligning an irradiating point of the spot beam with the reference point, it is possible to install the laser leveling device 1 to the reference point and to perform accurate positioning of the laser leveling device by the scanning line of the laser beam formed on a portion other than the spot.

This application is a division of Ser. No. 08/585,277 filed Jan. 11,1996 now U.S. Pat. No. 5,819,424.

BACKGROUND OF THE INVENTION

The present invention relates to a laser leveling device for emitting alaser beam in vertical or horizontal directions to scan and forproviding a reference line or a reference plane.

Positioning of a partition in a building or of a fluorescent lampmounted on a ceiling is performed according to a marking line drawn onthe floor, and the position indicated by the marking line is determinedby projecting the laser beam by a laser leveling device to ceilingsurface, wall surface, etc.

Referring to FIG. 9, description will be given on a conventional typelaser leveling device, in particular to a laser leveling device 1 forproviding a vertical reference line and a vertical reference plane.

A laser leveling device 1 comprises a main unit 2, having a projectionsystem, a control unit, a power supply, etc. incorporated in it, and arotating unit 3 having a pentagonal prism, rotated around a rotationaxis in horizontal direction, on the main unit 2. A laser beam emittedfrom the projection system in the main unit 2 is emitted in a directiontoward the rotation axis and in a direction perpendicular to therotation axis via the pentagonal prism. By rotating the pentagonal prismon the rotating unit 3, a vertical reference plane is formed. On the topsurface of the main unit 2, a bubble tube 4 is arranged, and three legs5 are mounted on the lower surface of the main unit 2. One of the legsserves as a leveling screw to perform leveling by the laser levelingdevice 1.

In the past, the operation to perform adequate positioning of the laserleveling device 1 has been carried out as follows:

The laser leveling device is divided into two types: a type, in whichthe rotating unit 3 itself is rotated, and a type, which is designed inwaterproof construction and in which only a rotating portion inside therotating unit 3 is rotated. In the former type, in which the rotatingunit 3 itself is rotated, positioning of the laser leveling device ismanually performed by the operator while rotating the rotating unit 3.In the latter type, which has a rotating portion incorporated in therotating unit 3, the rotating portion cannot be rotated from outside.Therefore, a mechanism must be specially arranged, in which a rotatingportion can be rotated mechanically from outside, or another mechanismmust be provided, in which a rotating portion can be electricallyrotated in normal or reverse directions at low speed by an electricswitch.

In the operation for adequate positioning of the laser leveling device,in case it is the device of the type, in which the rotating unit itselfis rotated, positioning marks 8 and 9, which coincide with each otherwhen the laser beam 10 is emitted in vertical downward direction fromthe rotating unit 3, are marked on the main unit 2 and on the rotatingportion of the rotating unit 3. The rotating unit 3 is manually rotatedto make the positioning marks 8 and 9 coincide with each other so thatthe laser beam is emitted in vertical downward direction from therotating unit 3. In case the irradiating point of the laser beam isaligned with a reference point on the floor, e.g. with the point ofintersection of the marking lines 6 and 7, and the scanning direction ofthe laser beam is aligned with the marking line 6, and the rotatingportion of the rotating unit 3 is rotated or is reciprocally rotatedwithin a given angular range to align a locus of the laser beam with themarking line 6. In a type of the laser leveling device, in which thelaser beam aligned with the rotation axis is emitted from the rotatingunit 3, the positioning of the device is performed in such a manner thatit is aligned with the point of intersection of the marking lines 6 and7, and that the irradiation point of the laser beam emitted in thedirection of the rotation axis is aligned with a reference point markedon an extension of the marking line 7.

Further, the same applies to a type, in which a rotating portion isprovided inside the rotating unit 3. By switching operation, therotating portion is properly rotated, the laser beam is irradiated invertical downward direction, and the irradiation point is aligned withthe reference point. Then, scanning direction of the laser beam isadjusted.

In the conventional type laser leveling device as described above, theadjusting operation must be done in two steps, i.e. a step to installthe device at the reference position and a step to adjust the scanningdirection after installing the device while moving the rotating portion.This involves complicated procedure and much working time. In the typeof the device, in which the rotating portion is incorporated inside therotating unit, the rotating portion cannot be rotated from outside.Thus, a mechanism must be provided, in which the rotating portion can berotated mechanically or electrically in normal or reverse directions.This results in more complicated structure.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a laser levelingdevice, by which it is possible to easily install the laser levelingdevice at a reference position and to adjust the position afterinstalling. It is another object of the present invention to provide alaser leveling device, which has a simplified structure. To attain theabove objects, the laser leveling device of the present inventioncomprises a light emitting unit for irradiating a laser beam, a rotatingunit for rotating the laser beam for scanning, and a means for turningoff the scanning laser beam so that a spotlike is formed in a specificdirection. The present invention also provides a laser leveling device,comprising a light emitting unit for irradiating a laser beam, arotating unit for rotating the laser beam for scanning, and a means forturning on the laser beam within a given angular range so that a lasermarker is formed in a specific direction. The present invention alsoprovides a laser leveling device, comprising a light emitting unit forirradiating a laser beam, a rotating unit for rotating the laser beamfor scanning, a means for turning off the laser beam within a givenangular range so that a laser marker is formed in a specific direction.The invention also provides a laser leveling device, in which the lightturn-off means comprises an angle detector for detecting an angle of therotating unit, a signal processing unit for issuing an on-off signal ofthe laser beam based on a signal from the angle detector, and a controlunit for performing on-off control of the light emitting unit based on asignal from the signal processing unit. The invention also provides alaser leveling device, in which the laser beam is turned off within agiven angular range before and after a specific direction to form a spotlight, or a laser leveling device wherein the laser beam is turned offso that a spot is formed in a specific direction, or a laser levelingdevice wherein the specific direction is at least one of verticaldownward direction, vertical upward direction or horizontal direction.The present invention also provides a laser leveling device, in whichthe light turn-off means is a slit plate having a slit hole for allowingthe laser beam to pass and arranged to interrupt the laser beam. Theinvention also provides a laser leveling device, in which the slit plateis provided in such manner that the slit hole on the slit plate ispositioned in vertical upward or downward direction of the rotation axisof the rotating unit. The present invention also provides a laserleveling device, wherein the laser beam is reciprocally scanned within agiven angle before and after the formed spot.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematical block diagram of an embodiment of the presentinvention;

FIG. 2 is an external view of the above embodiment;

FIG. 3 is a lateral cross-sectional view of an essential portion of anembodiment of the present invention;

FIG. 4 is a plan view showing an essential portion of the aboveembodiment;

FIG. 5 is a bottom view of an essential portion of the above embodiment;

FIG. 6 is a lateral cross-sectional view of an essential portion ofanother embodiment of the invention;

FIG. 7 is a perspective view showing operation of the device of thepresent invention;

FIG. 8 is a perspective view showing operation of the device of thepresent invention; and

FIG. 9 is an external view of a conventional type device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 represents a schematical block diagram of an embodiment of thepresent invention, in which the same component as in FIG. 9 is referredby the same symbol. The reference numeral 2 represents a main unit, and3 represents a rotating unit. First, description will be given on therotating unit 3.

On the main unit 2 of the device, a rotation support 16 is rotatablymounted. A pentagonal prism 15 is arranged and a driven gear 17 isconcentrically mounted on the rotation support 16. A driving gear 18 onoutput shaft of a scanning motor 19 is engaged with the driven gear 17.

Next, the main unit 2 is described.

An angle detector 11 for detecting rotation of the rotation support 16is provided, and a light emitting unit 12 having an optical axis alignedwith the rotation axis of the rotation support 16 is arranged. The angledetector 11 comprises a rotating disk and a detector. The rotating diskhas angle detecting slits provided over the total periphery at equalangular pitch and a 0-position detecting slit provided only at one pointover the total periphery. The detector comprises an encoder fordetecting the angle detecting slit and for issuing an angle pulse and aninterrupter for detecting the 0-position detecting slit and for issuinga 0 setting signal. The light emitting unit 12 comprises an opticalsystem 21 having a laser diode 20 and a collimator lens, etc. The laserbeam emitted from the laser diode 20 is collimated to parallel beams andis emitted toward the pentagonal prism 15 as parallel beams.

The main unit 2 comprises a signal processing unit 13, to which a signalfrom the angle detector 11 is inputted, and the signal from the signalprocessing unit 13 is inputted to a control unit 26, e.g. to a CPU. Thecontrol unit 26 issues control signals to a light emission control unit27 to drive the light emitting unit 12 and to a rotation control unit 28to drive a scanning motor 19 respectively.

Further, the signal processing unit 13 comprises an angle signalprocessing unit 22, a counter 23, a comparator 24, and a counterreference value setting unit 25. The signal from the angle detector 11is inputted to the angle signal processing unit 22, which processes thesignal, e.g. amplifies the signal, and inputs a pulse signalcorresponding to the angle signal to the counter 23. The counter 23counts the number of pulses from the angle signal processing unit 22,and the number of counts is outputted to the comparator 24 and thecontrol unit 26. The counter reference value setting unit 25 can set thenumber of pulses as desired, and the numerical value thus set isinputted to the comparator 24. The comparator 24 compares the numericalvalue set at the counter reference value setting unit 25 with thenumerical value from the counter 23. When these two values coincide witheach other, a coincidence signal is inputted to the control unit 26.Based on the coincidence signal, the control unit 26 outputs a lightemission control signal to the light emission control unit 27 andcontrols the light emission of the laser diode 20 via the light emissioncontrol unit 27. The control unit 26 issues a rotation control signal tothe rotation control unit 28 and controls the rotation of the scanningmotor 19 via the rotation control unit 28.

In the following, description will be given on operation of the devicereferring to FIG. 2.

The parallel laser beam emitted from the light emitting unit 12 isdeflected in a direction perpendicular to optical axis by the pentagonalprism 15 and is emitted from the rotating unit 3. The pentagonal prism15 is rotated by the scanning motor 19 via the driving gear 18 and thedriven gear 17. By the scanning of the laser beam emitted through thepentagonal prism 15, a vertical reference plane is formed by the laserbeam.

The 0 set signal from the interrupter of the angle detector 11 is set insuch manner that the laser beam is emitted in a direction by a givenangle ahead, e.g. by 30° ahead, from the position where laser beam isemitted in vertical downward direction. The 0 set signal is inputted tothe counter 23 via control unit 26.

When the 0 set signal is inputted to the counter 23, the count value onthe counter 23 is set to 0. On the comparator 24, a first preset countvalue corresponding to an angle slightly smaller than 30°, and a secondpreset count value corresponding to 30° or to an angle slightly largerthan 30°, and a third preset count value corresponding to 60° areinputted respectively by the counter reference value setting unit 25.

When the 0 set signal is inputted to the control unit 26 by the counter23, a light turn-off signal is issued to the light emission control unit27, and light emission from the laser diode 20 is stopped. Thecomparator 24 compares the signal from the counter 23 with the presetvalue from the counter reference value setting unit 25. When the numberof counts coincides with the first preset count value, a firstcoincidence signal is issued to the control unit 26. Based on the firstcoincidence signal, the control unit 26 issues a light emission controlsignal to the light emission control unit 27, and the laser beam isemitted from the light emitting unit 12.

Next, the comparator 24 issues a second coincidence signal to thecontrol unit 26 when the signal from the counter 23 coincides with thesecond preset count value. Based on the second coincidence signal, thecontrol unit 26 issues a control signal to the light emission controlunit 27 and stops light emission from the light emitting unit 12.Further, the comparator 24 issues a third coincidence signal to thecontrol unit 26 when the number of counts coincides with the thirdpreset count value. Based on the third coincidence signal, the controlunit 26 emits the laser beam from the light emitting unit 12 via thelight emission control unit 27.

As shown in FIG. 2, laser beam is emitted in spot-like manner invertical downward direction. The light is turned off within a givenangular range (30° in the above embodiment) from the vertical downwarddirection. Thus, a vertical reference plane is formed in the remainingrange.

To easily install the laser leveling device 1, the spot light is alignedwith the point of intersection of the marking lines 6 and 7 under theabove light emitting condition, and the locus on the floor as effectedby scanning of the laser beam is aligned with the marking line 6. Nospecial operation, such as stopping of the rotation of the rotating unit3 or the rotation at low speed, is required to install the laserleveling device 1.

It is needless to say that the angle for turning off the laser beam isnot limited to 30°. In the above embodiment, the light is turned offbefore and after except a part in vertical downward direction, whilelight may be turned off only in a part in vertical downward direction.The direction of the formed spot light is not limited to verticaldownward direction, and it may be in vertical upward direction or inhorizontal direction. Or, it may be directed simultaneously orselectively in four directions including vertical upward direction andhorizontal direction. The formed spot may be a point, a line segmenthaving a given length, or a laser maker (index marker).

Further, laser beam is rotated over total peripheral direction forscanning in the above embodiment, while it may be reciprocally scannedwithin a given angle, e.g. within the range of 30°, before and after thepredetermined range, e.g. the formed spot, or an inversion signal may beissued to invert when the number of pulses from the signal processingunit 13 reaches a given number so that reciprocal scanning can beperformed within the predetermined range. By reciprocal scanning withinthe limited range, the luminance of the spot increases, and thiscontributes to easier visual confirmation.

In the above embodiment, the light is turned off before and after thereference point of the scanning laser beam to form the spot light toirradiate the reference point. In the embodiment described below, lightis mechanically (physically) interrupted before and after the referencepoint to form the spot light.

Description will be given now, referring to FIGS. 3 to 8.

FIGS. 3 to 5 each represents an essential portion of the laser levelingdevice by removing the casing.

As already explained, the laser leveling device comprises a main unit 2and a rotating unit 3.

First, the rotating unit 3 is described. A rotation support 16 isrotatably mounted on the main unit 2. On the rotation support 16, apentagonal prism 15 is arranged and a driven gear 17 is concentricallyprovided. A driving gear 18 mounted on the output shaft of the scanningmotor 19 is engaged with the driven gear 17. The pentagonal prism 15deflects the light beam emitted in the direction of the rotation axis toa direction perpendicular to the rotation axis and allows a part 10c ofthe light beam to pass.

Next, the main unit 2 comprises a light emitting unit 12 having anoptical axis aligned with the rotation axis of the rotation support 16and a control circuit (not shown) in it. The light emitting unit 12comprises an optical system 21 having a laser diode 20 driven by a laseroscillator 14 and a collimator lens, etc., and the laser beam emittedfrom the laser diode 20 is emitted toward the pentagonal prism 15 asparallel beams.

On the top surface of the main unit 2, a guide groove 30 in parallel tothe rotation axis of the pentagonal prism 15 is formed, and an upperslit plate 31 is slidably engaged in the guide groove 30. The upper slitplate 31 has an elongated hole 32 at its base and is fixed on the mainunit 2 by a bolt 33, which is inserted through the elongated hole 32.Further, at the forward end of the upper slit plate 31, a slit hole 34is formed, which is positioned right above and in parallel to therotation axis of the pentagonal prism 15.

On the lower surface of the main unit 2, a lower slit plate 35 isslidably mounted in parallel to the rotation axis of the pentagonalprism 15 in similar manner to the upper slit plate 31. The lower slitplate 35 is fixed by screwing the leg 5 into the main unit 2. On theforward end of the lower slit plate 35, a slit hole 36 is formed, whichis right below and in parallel to the rotation axis of the pentagonalprism 15.

In the following, description will be given on operation of the device,referring to FIGS. 7 and 8.

The bolt 33 and the leg 5 are loosened to move the upper slit plate 31and the lower slit plate 35 backward, and these slit plates are fixed bytightening the bolt 33 and the leg 5 again. The upper slit plate 31 andthe lower slit plate 35 should not interfere with the laser beam 10.Further, the leg 5 is adjusted to install the main unit 2 in horizontalposition using bubble tubes 4a and 4b.

By driving the laser oscillator 14, the laser beam is emitted from thelight emitting unit 12. A part of the parallel laser beam emitted fromthe light emitting unit 12 passes through the pentagonal prism 15, andthe remaining part of the laser beam is deflected in a directionperpendicular to the optical axis by the pentagonal prism 15 and isemitted from the rotating unit 3. The pentagonal prism 15 is rotated bythe scanning motor 19 via the driving gear 18 and the driven gear 17. Byscanning of the laser beam emitted through the pentagonal prism 15, avertical reference plane is formed.

To align the scanning locus of the laser beam 10 with the marking line6, the bolt 33 and the leg 5 are loosened to pull out the upper slitplate 31 and the lower slit plate 35 so that the laser beam 10 crossesand passes through the slit holes 34 and 36.

Because the upper slit plate 31 and the lower slit plate 35 are present,the laser beam 10 emitted from the rotating unit 3 is interrupted beforeand after the slit holes 34 and 36. As a result, the laser beam 10passing through the slit holes 34 and 36 is turned to spot lights 10aand 10b, which are emitted in vertical direction upward and downwardrespectively.

To easily install the laser leveling device 1, the spot light 10b isfirst aligned with the point of intersection of the marking lines 6 and7 under the light emitting condition as described above and the locus onthe floor as effected by scanning of the laser beam is aligned with themarking line 6. It is needless to say that no special operation isrequired such as stopping of the rotation of the rotating unit 3 orrotating it at low speed to install the laser leveling device 1.

Further, a part of the laser beam 10, i.e. the light beam 10c, emittedin axial direction of the rotating unit 3 projects a point, i.e. thepoint of intersection of the light beam 10c and the marking line 6, onwall surface.

Here, the relationship between the spot lights 10a or 10b and the lowerslit plate 35 is described. In the setting of the laser leveling device1, if we assume that the distance from optical axis of the lightemitting unit 12 to ground surface is A, the distance from the opticalaxis to the lower slit plate 35 is B, and the width of the slit hole 36is C, then the width of laser irradiation on the ground surface is givenas:

    D=(C/B)×A                                            (1)

If the slit width with respect to the diameter of the emitted light beamis taken into account, the irradiated laser hole on the ground surfaceis turned to a point. Showing an example by substituting numericalvalues, if it is assumed that A=100 mm, B=50 mm, and C=0.5 mm, then D isobtained from the equation (1) as:

    D=(0.5 mm/50 mm)×100 mm=1 mm                         (2)

Here, if the width of the irradiated laser beam is set to 1 mm, thelaser irradiation projected on the ground surface is approximately inspot-like shape.

In case the laser leveling device 1 is tilted at the time ofinstallation, the position of the slit hole 36 is deviated in thevertical downward direction from the point of intersection. Thus, theposition of the irradiation spot is deviated in the vertical downwarddirection from the point of intersection. As a result, it is possible toobtain an accurate and stable irradiation spot by adjusting the devicein horizontal position using the bubble tubes 4a and 4b.

With regard to tilting of the light emitting unit 12 within the verticalplane including the optical axis, the optical axis itself iscompensated. Thus, even when the slit hole is tilted, the irradiationspot does not move.

With regard to tilting within a plane perpendicular to the optical axis,the irradiation spot moves as described above. For example, if theleveling of the device is adjusted using a bubble tube of 1'/1 div.,even when there is a reading error of one graduation, the spot moves by0.03 mm in case A=100 mm, as described above, and this causes no troublein practical operation.

As described above, it is designed that the slit plates 31 and 35 can bemoved in and out with respect to the vertical laser irradiation plane.Therefore, when lower marking operation is performed after theinstallation of the device, the light beam is not hindered and notrouble occurs in the operation.

Further, for the purpose of the positioning operation only of the laserleveling device 1, the upper slit plate 31 is not required. By providingthe upper slit plate 31, the device can be turned to a rotary laserdevice equipped with a vertical unit. By adopting the upper slit plate31, it is possible to attain the purpose with high accuracy, i.e. toirradiate the spot light 10a in vertical upward direction, to projectground marking on ceiling, or to align in vertical direction.

The extent of interruption of the spot light by the upper slit plate 31and the lower slit plate 35 to form the spot lights 10a and 10b isdetermined by adequately selecting the widths of the upper slit plate 31and the lower slit plate 35. Further, it is needless to say that theslit plates can be provided on lateral sides of the main unit 2.

In FIG. 6, an encoder 37 is provided on the rotation support 16 of theabove embodiment. By this encoder 37, it is possible to control positionand range of the scanning. Similarly to the case where the slit plate 35is arranged face-to-face to the laser irradiation plane rotated andirradiated, the laser spot can be obtained by arranging the slit plate35 at the desired position and to perform reciprocal scanning toward theslit plate 35. Under this condition, an irradiation spot with higherluminance can be attained by utilizing the scanning laser irradiationbeam having partially high average luminance.

As described above, it is possible according to the present invention toperform positioning of the laser leveling device in simplifiedarrangement and without requiring special operation and to align thevertical laser plane formed by the laser leveling device with thedesired position with high accuracy.

What is claimed is:
 1. A laser leveling device, comprising a lightemitting unit for irradiating a laser beam, a rotating unit for rotatingsaid laser beam from said light emitting unit for scanning and forforming a reference plane, and a slit plate positioned so that saidlaser beam from said rotating unit crosses said slit plate, said slitplate having a predetermined width and having a slit hole for allowingsaid laser beam to pass so that a spot or a segment is formed.
 2. Alaser leveling device according to claim 1, wherein said slit plate ispositioned in a downward direction so that a laser spot is formed in avertical downward direction when a vertical reference plane is formed bysaid rotating unit.
 3. A laser leveling device according to claim 2,wherein said slit plate can enter and exit from a position where thelaser beam from said rotating unit crosses said slit plate.
 4. A laserleveling device according to claim 1, wherein said slit plate ispositioned in an upward and downward direction so that a laser spot isformed in vertical upward and downward directions when a verticalreference plane is formed by said rotating unit.
 5. A laser levelingdevice according to claim 4, wherein said slit plate can enter and exitfrom a position where the laser beam from said rotating unit crossessaid slit plate.
 6. A laser leveling device according to claim 1,wherein said slit plate can enter and exit from a position where thelaser beam from said rotating unit crosses said slit plate.
 7. A laserleveling device according to claim 1, wherein said rotating unit has anencoder for detecting a rotating angle of said rotating unit and saidscanning of said laser beam is controlled within a given range and agiven position so that said laser beam from said rotating unit crossessaid slit plate in response to the detection by said encoder.